One of the most interesting watches currently on display at the Vacheron NY Boutique is the openworked $20 Liberty Head double eagle gold coin watch. Excluding the complexity of the case, it houses the least complicated mechanical watch in Vacheron's collection - manual winding, with hours and minutes only. Of course, this is no ordinary movement. Concealed within the coin is a skeletonized version of the world's thinnest mechanical wristwatch movement in production, the cal. 1003, measuring just 1.64 mm thick.

As detailed by Vacheron's Alex Ghotbi, the brand has a long history of producing watches integrated into coins, going back to approximately 1850, with their first coin wristwatch perhaps produced as early as 1938.

The watch's case is much more complicated than it appears, as it's comprised of two cases. The exterior case, which appears to be formed from a single coin, is in actuality derived from two coins. The face is cut from the first coin to form the cover, and the second coin is hollowed out to form the exterior case's base.

The face of the coin opens to reveal the watch by pressing a pusher on the side of the case at 3 o'clock. Skeletonized beautifully, the cal. 1003 is embellished with exquisite hand engraving on the remaining components.

The watch itself is housed in a second, extremely thin case hinged to a solid 18 karat gold flange within the exterior case. This allows the watch to be lifted out, such that when off the wrist, it can be used as a miniature desk or table clock. Even when on the wrist, with the watch lifted, both sides of the movement can be admired at once...awesome!

The skeleton work done on the movement is magnificent...

Check out how thin the inner case is...

The skeletonization is as good as it gets...in spite of the movement's extremely small dimensions, there's wonderful transparency and airiness allowing one to see through the movement...

A view inside the exterior case and cover, showing the fine perlage finish...

Vacheron adds a reeded rim around the circumference of the case that duplicates the look found on the original coins. Amazingly, with two cases, the overall thickness of the watch measures just 4 mm! This is about double the thickness of the original coin, which measures approx. 2 mm.

Straight lugs secure the strap to the coin...

A view of the caseback...

The $20 open worked is a wonderful Métiers d'Arts piece showcasing Vacheron's leading know-how as a case and watchmaker.